Accumulation effect of SiO2 protective layer on multi-shot laser-induced damage in high-reflectivity HfO2 /SiO2 coatings

• 来源期刊: 中国光学快报（英文版）
• 年，卷（期）: 2011,（11）
• 页码范围: 90-93
• 页数: 4页
• 语种: 英文
• DOI: 10.3788/COL201109.103103

摘要

The accumulation effects in high-reflectivity (HR) HfO2/SiO2 coatings under laser irradiation are investigated.The HR HfO2/SiO2 coatings are prepared by electron beam evaporation at 1 064 nm.The laser-induced damage threshold (LIDT) are measured at 1 064 nm and at a pulse duration of 12 ns,in 1-on-1 and S-on-1 modes.Multi-shot LIDT is lower than single-shot LIDT.The laser-induced and native defects play an important role in the multi-shot mode.A correlative theory model based on critical conduction band electron density is constructed to elucidate the experimental phenomena.In recent years,many laboratories have investigated multi-shot laser-induced damage in optical materials,such as fused silica[1] and KTP crystals[2].The multishot laser-induced damage threshold (LIDT) is often lower than single-shot LIDT because of the accumulation effects in most optical materials[1,3-5].As a result,investigations on multi-shot laser-induced damage in optical coatings are of high practical importance for high-power laser applications[5,6].The mechanism for single-shot laser damage includes avalanche ionization (AI)[7],multiphoton ionization (MPI) [8],impurity breakdown[9],etc.